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Variable Schema

1. CRF abbreviation: case insensitive, no numbers (optional)
2. Underscore _   
3. Question number (2 digits or characters, use 0 placeholder)      
4. Underscore _      
5. Sub-question number (2 digits or characters, use 0 placeholder)      
6. Underscore _      
7. Short descriptor <=10 characters, can use camel case      
8. Underscore _      
9. Optional descriptor modifiers 
   1. Subject identifier (important if mother, child, father connected by same study ID)      
      1. mo = mother     
      2. fo = father     
      3. ch = child
      4. pa = parent /caregiver
   2. Variable type       
      1. bn = binary (0,1) 
      2. yn = yes no
      3. sp= specify (free text) 
      4. dt = date
      5. dttm = date and time
10. Underscore _ 
11. Event identifier      
1. nA = Antenatal e.g. A, 20A, 36A : antenatal, 20 weeks antenatal, 36 weeks antenatal      
2. B = Birth      
3. nW= where n is a digit and W is weeks      
4. nM = where n is a digit and M is Months      
5. nY = where n  is a number  and Y is year 

Variables should be limited to 28 characters so that a suffix or prefix can still be added. Do not include the unit of measure in the variable name (will be specified in study procedures).